Evaporation techniques are used extensively in chemistry and biology laboratories to separate a relatively volatile component from a liquid mixture, or to concentrate or dry compounds in solution.
In use, the pressure within an evaporator is reduced to a point at which the liquid component to be evaporated will boil at temperature that will not damage other components of the sample.
In known evaporators, centrifugal forces are often employed in order to reduce expulsion of the solution from the sample surface during heating by a process known as “bumping”, which otherwise causes spillages and contamination of the evaporator.
Various methods are used to heat samples within an evaporator. Principally, irradiation is employed due to its ability to transmit through a vacuum. Two existing techniques involve, respectively:
1. The use of a conductive barrier in contact with the samples to receive the irradiation and prevent direct incidence of irradiation on the sample containers. The sample temperature may be closely monitored by measuring the temperature of the barrier, thereby allowing accurate temperature control to prevent the maximum sample temperature being exceeded; and
2. Direct irradiation of the sample containers.
A drawback of the first technique is that fabrication of a suitable barrier may be complex and costly. Also, the barrier may reduce the ability to transfer heat efficiently to the sample. With regard to the second technique, overheating of the samples may be prevented by making the source no hotter than the maximum sample temperature, but this substantially limits the rate of heat delivery.